The present invention relates to an enddscope having a channel for guiding an operating tool such as forceps to be used in removing a foreign body in the body cavity.
As is known in Jpn. UM. Appln. Publication No. 59-48601, an endoscope has a tube externally attached thereto. The tube has a channel for passing an operating tool therethrough and used by attaching it to the main body as occasion requires. The externally-provided tube extends from the control section of the endoscope to a distal end of an insert. The external tube is attached to the insert in such a way that the distal end face of the insert forms the same plane as that of the distal end face of the external tube. When the operating tool is inserted through the tube channel, a distal end of the operating tool is abutted against an observation window formed at the distal end face of the endoscope insert.
When a polyp is removed by using the endoscope thus constructed, if the foreign body is picked up by a foreign-body removing tool inserted through the external tube, the polyp is inevitably positioned in front of the distal end of the endoscope, narrowing the observation field and working area for the operating tool. Hence, in general, once the foreign-body removing tool grabs a polyp, it is difficult to cut away another polyp. As a result, the entire endoscope has to be removed out of the body every time the pick-up tool grabs a polyp.